Input: adbhid - fix OOPS introduced by dynalloc conversion

The problem is that adbhid[]->input is NULL, so the kernel oopses with
a null pointer dereference as soon as a key is pressed.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>